Columbia - Cooling the Breach

"James Garry" wrote in message ...
"Craig Fink" wrote in message
rthlink.net...

From page 89 of:

/boss.steamos.com/download/caib/documents/20030711/sts107workingscenario.pdf
Assume the average stagnation heat flux during entry = 40 BTU/ft^2/sec

Sadly this is a Very Small number and it translates to maybe 50 J/ft**2/s,
maybe 450 J/m**2/s, which is almost three orders of magniture smaller than
actual stagnation fluxes for objects with nose radii of a metre or so.
http://hypersonic2002.aaaf.asso.fr/papers/17_5264.pdf

Pointier geometries will see higher fluxes and temperatures.

Also, entry heating is much briefer than you suggest, the heating pulse
generally lasts for a few to a few tens of seconds.

-James Garry


I seem to recall that the Apollo reentry had a 3 minute communications blackout.

Zoltan

Gordon D. Pusch wrote:
(Zoltan Szakaly) writes:

I wonder why they did not make the skin under the tiles out of
titanium, at least around the leading edges. Titanium is a poor heat
conductor. I bet the Buran has Ti skin.

The Russians happen to have a large fraction of the worlds's supply of titanium.
(Most of the rest of it belongs to South Africa.) The Russians have so MUCH
titanium that they can afford to make common implements out of the stuff ---
whereas non-miltary projects in the U.S.A. must make do with lesser materials,
such as Aluminum or steel.

Uhh... Titanium is teh 9th most abundant element in Earth's crust. For what you say
to be true, significant portions of russia and south africa would need to be made
of quite pure titanium. As for military vs civilian use of titanium, most of
white paint is titaium dioxide based tehse days (unless it is lead paint).



-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'

--
Sander

+++ Out of cheese error +++

Sander Vesik writes:

Gordon D. Pusch wrote:
(Zoltan Szakaly) writes:

I wonder why they did not make the skin under the tiles out of
titanium, at least around the leading edges. Titanium is a poor heat
conductor. I bet the Buran has Ti skin.


The Russians happen to have a large fraction of the worlds's supply
of titanium. (Most of the rest of it belongs to South Africa.)
The Russians have so MUCH titanium that they can afford to make common
implements out of the stuff --- whereas non-miltary projects in the
U.S.A. must make do with lesser materials, such as Aluminum or steel.

Uhh... Titanium is teh 9th most abundant element in Earth's crust. For
what you say to be true, significant portions of russia and south africa
would need to be made of quite pure titanium. As for military vs civilian
use of titanium, most of white paint is titaium dioxide based tehse days
(unless it is lead paint).

Aluminum is even an order of magnitude MORE abundant in the crust than
titanium --- but good luck trying to produce an ingot of pure aluminum
metal from radnom dirt or rocks that you dug up out of your backyard!

To produce metallic titanium currently requires reducing high-grade
ilmenite or rutiler ore with chlorine gas in the presence of carbon;
ilemenite and rutile ore of sufficiently high grade are primarily found
in isolated "placer" deposits in a few locations. The primary exporters
of high-grade ilmenite and rutile ore suitable for metallic titanium
production are South Africa, Australia, and Canada. (Russia presumably
also has similar high-grade titanium ore deposits, but apparently must
be using most of that high-grade ore internally, rather than exporting it.)


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'

Sander Vesik wrote:
Uhh... Titanium is teh 9th most abundant element in Earth's crust. For what you say
to be true, significant portions of russia and south africa would need to be made
of quite pure titanium. As for military vs civilian use of titanium, most of
white paint is titaium dioxide based tehse days (unless it is lead paint).

Historically, titanium dioxide is not used as an ore- it's too difficult
to separate. The Russian mines produced the vast majority of the useable
titanium in the world, which gave America difficulties with certain
projects such as the SR-71. They resorted to setting up a fake company
in Europe and buying the titanium and then sneaking it across to America ;-)

However an electrolysis process has now been discovered that can use
titanium dioxide, and so titanium is getting rather cheaper, and
titanium dioxide is far more abundant.

-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'

In article ,
Sander Vesik wrote:
Gordon D. Pusch wrote:
(Zoltan Szakaly) writes:

I wonder why they did not make the skin under the tiles out of
titanium, at least around the leading edges. Titanium is a poor heat
conductor. I bet the Buran has Ti skin.

The Russians happen to have a large fraction of the worlds's supply of titanium.
(Most of the rest of it belongs to South Africa.) The Russians have so MUCH
titanium that they can afford to make common implements out of the stuff ---
whereas non-miltary projects in the U.S.A. must make do with lesser materials,
such as Aluminum or steel.

Uhh... Titanium is teh 9th most abundant element in Earth's crust. For what you say
to be true, significant portions of russia and south africa would need to be made
of quite pure titanium. As for military vs civilian use of titanium, most of
white paint is titaium dioxide based tehse days (unless it is lead paint).

I also recalled the old USSR as having had much of the world's Ti,
so I went info-hunting.

My admittedly oldish (1971) 18th edition of Dana's Manual of
Mineralogy has ilmenite (FeTiO3) as the primary titanium ore, and
says that there are "large quantities [...] in Norway; in Finland;
and in crystals at Miask in the Ilmen Mountains, U.S.S.R." The
mineral was named after this last locality, in fact. Rutile (TiO2)
is much more common, but is listed as a secondary source. In fact,
ilmenite is given as the primary source ore for industrial TiO2,
surprisingly.

Subsequent developments in processing technology may have made
rutile a more attractive Ti ore nowadays; I don't keep up with this
field at all (though I never toss a good reference book ;-). But it
was certainly true until fairly recently that the world's primary
supply of Ti ore was ilmenite, whose occurence is much more limited.
This may explain Gordon's memory; it certainly does mine.

greg
================================================== ==================
Greg Titus Programming Environment Tools
Cray Inc.
505-995-0835
--
================================================== ==================
Greg Titus Programming Environment Tools
Cray Inc.
505-995-0835

Ian Stirling wrote:

Zoltan Szakaly wrote:
snip
I wonder why they did not make the skin under the tiles out of
titanium, at least around the leading edges. Titanium is a poor heat
conductor. I bet the Buran has Ti skin. I wonder if it would be
expensive to reactivate the two Buran orbiters the russians have/or
had.

Ti isn't that great at high temperatures, at 700C, it undergoes a
phase transition,


We're not talking about heating the entire structure, just a damaged area
and how long the material stays around to protect the rest of the
structure. Even after the beta transition, and the titanium isn't
structural, the load will redistribute itself through other structural
members that aren't hot. I would think even none structural titanium would
stop the plasma from penetrating further into the structure, until it melts
and goes away.

Also some titanium alloys have delayed transition, closer to 1000C.

Craig Fink

Ian Woollard wrote:

Historically, titanium dioxide is not used as an ore- it's too difficult
to separate.

All titanium ores are oxides, and in the Kroll process they get converted
to titanium tetrachloride first, so the exact composition of the ore is
not all that important.

Paul

Gordon D. Pusch wrote:

Aluminum is even an order of magnitude MORE abundant in the crust than
titanium --- but good luck trying to produce an ingot of pure aluminum
metal from radnom dirt or rocks that you dug up out of your backyard!

To produce metallic titanium currently requires reducing high-grade
ilmenite or rutiler ore with chlorine gas in the presence of carbon;
ilemenite and rutile ore of sufficiently high grade are primarily found

No. there is a number of ores that can be processed to a rutile like
substance by pre-processing steps on which then the rutile process
can be applied.


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'


--
Sander

+++ Out of cheese error +++

(Gordon D. Pusch) wrote:
The Space Scuttle was technically a "civilian," =NOT= a military project,
(despite its milspec cost overruns (which were largely due to Rockwell
illegally using the Scuttle to prop up the B-1 Bomber Division while
Rockwell was waiting for Carter to lose the next election to a Republican,
after Carter canceled the B-1 Bomber program). Hence, at the time, Rockwell
was not =ALLOWED= to use titanium for a "civilian" project like the Scuttle...

Rockwell wasn't allowed to use titanium because of large projected
uses elsewhere (F-14, F-15 among other things). It was feared that
the available supply would not support the projected demand.

D.
--
The STS-107 Columbia Loss FAQ can be found
at the following URLs:

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Corrections, comments, and additions should be
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